APPLICANT'S ABSTRACT: This is a proposal to study the predisposing properties of tobacco for cocaine use. We plan to re-contact as adults, subjects who have been participants since 1974 in a longitudinal study of ADHD and other childhood behavior problems. The goal is to determine more precisely the developmental course of the tobacco-cocaine connection from adolescence through adulthood. In consultation with expert collaborators, a set of interview procedures and questionnaires will be devised that reliably assess the qualities of the first and subsequent experiences with tobacco, cocaine, and other relevant substances. More specifically, we seek to explore more thoroughly the possibility of tobacco as a sensitizing agent in the use of cocaine among these subjects. Thus, while it has been established that the use of tobacco temporally precedes use of illegal drugs, no research in humans has been conducted that could assess the effects of preexposure to tobacco as a sensitizing agent in the uptake and abuse of the illegal drugs, most notably cocaine. Evidence from the animal literature, however, has demonstrated that preexposure to both nicotine and amphetamine compounds predisposes rats to the reinforcing impact of cocaine. Many of the participants in this longitudinal study are both heavy tobacco users and/or have been treated with amphetamine. Questions to be answered include: 1) What is the proportion of variance in frequency of usage and initial reaction to cocaine that may be attributed to tobacco preexposure?; and, 2) Does the pattern and progression of drug use from adolescence through young adulthood differ in the ADHD and control groups? In consultation with expert collaborators, a set of interview procedures and questionnaires will be devised that reliably assess the qualities of the first and subsequent experiences with cocaine, marijuana, stimulants, and tobacco. Multivariate statistical procedures including scalogram analysis and multiple regression will be used to address the questions of the study. Answers to these questions are expected to augment the knowledge necessary to target specific groups, ages, and/or developmental periods where educational and other social interventions may be most sensitive.